1. Field of the Disclosure
The disclosure relates generally to data communications, and in particular, to providing data over cable television networks.
2. The Prior Art
Background
FIG. 1 is a block diagram of a prior art cable switching system 100. The system 100 is typically disposed within a data-over-cable system, such as cable TV or broadband system. An upstream and a downstream data channel are typically provided, with the data flowing from the data provider (the head end side) to the consumer residence referred to as the downstream (DS) channel, and the converse being the upstream (US) channel.
FIG. 1 illustrates an upstream embodiment as indicated by the flow direction of the data. A downstream version will simply have the data flow in the opposite. The unit 100 is typically disposed within a chassis 110, and is fed by upstream data labeled US1 in through USn in. Each data stream is fed to a corresponding working channel (WC) switch WC1 through WCn. The switches are configured to provide an output US1 out through USn out, and a protection output to a switch SW. The switches are powered through a power source 120.
In normal operation, the working channel switches WC1 through WCn feed a corresponding linecard located at the head end. To provide fail-over support, the signal feeding the working channel corresponding to the failed linecard is routed to a redundant linecard through the switch SW in the event that a linecard fails in the head end.
However, the working channel switches WC1 through WCn are active devices that have a relatively short lifetime. Hence, if the unit loses power, the switches will not function.